PORTLAND, Oregon -- The130-foot trimaran docked Thursday on the Willamette River is miserly enough on fuel to make a slow journey around the world without once stopping for a refill.

The narrow hull -- stabilized by two outriggers -- can survive in up to 30-foot seas. And, in what may foreshadow a new chapter in maritime history, it is designed to operate without any humans on board.

"This here is the look and shape of things to come," said Rear Adm. Robert Girrier, the Navy's director of unmanned warfare systems. "We are excited to learn from this amazing vessel and how we can team with it."

This prototype was developed by the Defense Advanced Research Projects Agency, or DARPA, in a five-year, $120 million program that tapped some of the technology used by unmanned spacecraft.

It was christened in Portland on Thursday as the Sea Hunter in a ceremony attended by senior Defense Department officials and contractors. The vessel will be headed to California for two years of tests with the Navy.

Unarmed and equipped with sonar, it is designed for anti-submarine warfare that may involve tracking of undersea diesel-electric subs.

But Defense Department officials say unmanned vessels could one day be used in many different ways, including to countermine actions and cargo transport. The ships also might be armed for maritime conflicts, though Defense Department officials say the decision on when to use force would remain under human control.

Defense Department officials believe the Sea Hunter could help set the stage for a push to develop civilian use of unmanned vessels.

"There is absolutely no reason why a ship couldn't sail across the Pacific delivering cars to the United States with no people on board. It would be extremely inexpensive," said Robert Work, deputy secretary of defense. "As long as we prove ... that these vessels are safe."

Still, the concept of an unmanned vessel initially generated plenty of skepticism as officials tried to get the project started.

"There were a lot of people who wanted to kill the program. We weren't getting a lot of love from the Navy," said Scott Littlefield, manager for the program that oversaw development of the vessel. "We spent a lot of time walking around the Pentagon to figure out what their concerns were."

Project contractors included Vigor Industrial, which owns the shipyards in Oregon where the vessel was built. Washington workers also pitched in, including Janicki Industries, a Sedro-Woolley supplier that provided hull and deck molding, according to a Vigor official.

For the initial testing, the vessel has a bolt-on wheelhouse for crew who, with the press of a red button, can take control of the craft.

DARPA and the Navy must show that an unmanned vessel can meet international regulations for preventing collisions at sea. One area that still needs work is the vessel's ability to respond to sailboats that it might encounter, officials said.

Once the Sea Hunter can meet international standards, the intent is for the wheelhouse to be removed and the vessel to take to sea with no humans on board.

While military aerial drones are typically remotely operated, DARPA officials say the Sea Hunter would need only to be monitored by a human. They envision a day when one person might watch over a whole flotilla of the vessels, which could be built for about $20 million each.

During a Thursday tour, the ship's hull was divided into separate compartments that included an engine room and an air-conditioned space for five computer servers.

The server system is built with lots of redundancy so if something fails, the vessel won't lose its operating abilities, said Robert McCummins, who works with Leidos -- the project's prime contractor -- as a chief engineer.

So far, the vessel has yet to undergo sea trials. Instead, it has motored in river waters at speeds of up to 31 mph.

And it has been a strange sight for the sport fishermen out on the water searching for spring chinook.

"They would call us up and say, 'What's that, a submarine?' We would say, 'Nope, not a submarine,'" McCummins said. "But we couldn't give a lot more information over the radio."

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This article was written by Hal Bernton from Seattle Times and was legally licensed through the NewsCred publisher network.